Asthma is an allergic inflammatory disorder characterized predominantly by an eosinophilic infiltrate into the airways. Eosinophils are thought to be the major effector cells mediating tissue injury and hyperresponsiveness. Therefore, it is likely that blocking the mechanisms responsible for the selective emigration of eosinophils could result in attenuation of the disease. Eotaxin, a potent and selective chemokine for eosinophils, signals through the chemokine receptor CKR3 which is exclusively expressed on eosinophils. Because of their eosinophilic specificity, eotaxin and CKR3 may play a pivotal role in the preferential migration of eosinophils into the airways. Consequently, CKR3 would appear to be an attractive target for drug development. The goal of Phase I research is to identify potent eotaxin analog antagonists. In addition, we expect to obtain information on the molecular basis for eotaxin binding and signalling through CKR3 which will be valuable for drug design. We will study the nature of the molecular recognition between eotaxin and its receptor using a mutational and functional approach. Specifically, we will: 1) Express, purify and characterize a) site directed point mutations of eotaxin, b) N-terminal extensions of eotaxin, and c) hybrid chemokines; 2) Characterize the binding and functional properties of the eotaxin mutants in in vitro assays using human eosinophils and CKR3 cell transfectants; 3) Evaluate the binding and functional properties of antagonists using eosinophils from species appropriate for in vivo asthma studies. PROPOSED COMMERCIAL APPLICATION: The long-term goal of this project is the development of antagonists for CKR3 potential therapeutics for asthma. Phase I studies could identify an antagonist that might have commercial potential. In long-term goal of this project is the development of antagonists for CKR3 potential therapeutics for asthma. Phase I studies could identify an antagonist that might have commercial potential. In addition, these studies could also provide valuable information for rational drug design.